Tailoring the Degree of Polymerization of Low Molecular Weight Cellulose

Abstract

The degradation of cellulose to lmw samples with $\overline {DP} _{{\rm w}} $ varying from 15 to 130 is investigated. Cellulose samples prepared from the hydrolysis of regenerated cellulose fibers in dilute HCl possess $\overline {DP} _{{\rm w}} $ = 50. Applying homogenous degradation of microcrystalline cellulose in H3PO4 at RT for 3 weeks, samples with $\overline {DP} _{{\rm w}} $ = 35 and a PDI of 1.58 are obtained. Decreasing the hydrolysis temperature to 8 °C results in lmw cellulose with $\overline {DP} _{{\rm w}} $ > 70. Fractionation in DMA/LiCl provides samples with $\overline {DP} _{{\rm w}} $ = 12 to 130, together with a narrow molecular weight distribution. Detailed structural analysis by 2D NMR spectroscopy reveals that the prepared lmw celluloses are suitable as mimics for cellulose. magnified image

Supercritical water hydrolysis: a green pathway for producing low-molecular-weight cellulose

“…26 In this regard, SCWT can be a solid alternative to the existing pathways for partially depolymerising cellulose as well as for producing low-molecular-weight cellulose (LMWC), thereby closing the existing DP availability gap between the short-chain oligomers and MCC. 24 LMWC is extensively formed as an intermediate compound during supercritical water hydrolysis. The chains are dissolved in nearcritical and supercritical water but the oligomers with a DP above 6 have very limited solubility in ambient water; this difference causes the longer cello-oligosaccharides, or water-insoluble low-molecular-weight cellulose (WI-LMWC), to slowly precipitate after the reaction.…”

Hybrid Fe3O4@amino cellulose nanoparticles in organic media – Heterogeneous ligands for atom transfer radical polymerizations

“…Microcrystalline cellulose, Avicel PH 101, was purchased from Fluka with DP = 250, and cellulose with DP = 50 was achieved after degradation of the regenerated fibers [40]. All solvents and reagents were purchased from Acros or Sigma-Aldrich and were purified as recommended elsewhere [41].…”

Alkyl β-d-cellulosides: non-reducing cellulose mimics

“…Two types of model compounds should be distinguished: (a) mimics with additional OH functions at terminal anhydroglucose units (AGU, OH at position 4 of the non-reducing end and OH at C-1 of reducing end), (b) mimics with protection of one or both terminal OH moieties. Recently, we have developed efficient approaches for the preparation of mimics covering a wide DP range with non-protected end groups (Liebert et al 2008;Meiland et al 2011). In case of cellulose mimics with small DP-values, the reactivity of a carbonyl moiety at C-1 of the reducing end group (REG) was still visible during reactions and NMR analyses, and therefore may significantly influence the studies mentioned.…”